Eric wrote: > I am getting 2100 rpm with a 52/48 prop static.The engine runs very > smoothly,and responds well but on increasing throttle at 2100 rpm the > engine quietens and revs drop.On throttling back I can get 2100 again and > very smooth running.The engine is a 2 l VW as new,running on twin > Zenith/stromberg carbs.Ignition (for now) is a VW Points distributor.with > centrifugal advance and vacuum advance.I intend going for a Compufire > ignition system with backup, later on,but would like to hear your views,on > this engine going quiet and rev drop on increasing throttle above 2100 > revs static.<
Sounds like the timing is retarding at higher throttle settings, which would not be surprising if you have the vacuum advance/retard unit plugged into the wrong kind of vacuum source. You need to make absolutely sure that the timing is doing what you think it's doing, and understand fully the operation of that particular distributor and the vacuum sources that operate it. Most folks replace the stock distributor with something with pure mechanical advance (like the Bosch 009). It makes timing dirt simple. You set it up for a maximum advance of something like 30-32 degrees BTDC at full throttle (which ought to be over 2500 rpm, for sure), and then readjust idle speed for whatever advance you get at idle. Mark Langford email: N56ML "a" hiwaay.net website: www.N56ML.com >
